Two problems with many people that are religious: ego inflation, and OCD (Obsessive Compulsive Disorder).

The problem with religion was noticed by Sapolsky.[Robert Sapolsky at Stanford]
The problem is that of motivation as it relates to schizoid personalities.
That is, since as the Ari says most of this world is evil, we have to assume the majority of people obsessed with religion are doing it from the standpoint of Schizoid personalities. [Their obsession with ritual and sex is really a form of OCD.]
And that also means those that are obsessed with religion from the standpoint of trying to disprove some religion, or all religion, are also coming from the standpoint of a a schizoid  personality.

But we also know of authentic mystics and tzadikim that were God filled. Their service towards God was certainly not from some personality defect. Some example might be Bava Sali or the Gra or the Rambam.

The way I think to deal with this is from the idea of Dr. Kelley Ross--that of intention.[That is he solves the problem of Ontological undecidability by means of intention and that is what I think makes the main difference here also.]

The other problem with religion I noticed is ego inflation. This can either be a flattering image of one's self as some kind of central world figure. Or it can refer in its beginning stages to one's group. In either case it is a terrible mental disease. And it exists in all religious teachers that I have seen. And in fact in a large majority of religious people.
Both effects OCD (Obsessive Compulsive Disorder) and Ego Inflation are direct results of what Kant called "Antimonies."That is contradictions that results when pure reason enter into areas of the dinge an sich.